nostr:npub1qtkdu9s8mnygvkcvycw0wtmp85t95v25v8eyavtkx2q0nhnuxmnq9txqrw 

Perhaps the highest degree of the terms in the equations matters too? 

There is a loose sense in which a model with nonlinear terms is more complex than one with only linear terms, right? 

dx/dt = -a x

vs

dx/dt = - a x ^ 2

Both have the same number of free parameters, but arguably the second is more complex?